Positive electrode films for alkali metal polymer batteries and method for making same

ABSTRACT

A process for extruding a thin positive electrode sheet having at least 40%/wt of solid content for a lithium polymer battery through a single or twin screw extruder is disclosed as well as a positive electrode sheet produced therefrom. A mixture of active cathodic intercalation material, lithium salt and electronic conductive material is mixed with a polymer of the polyether family in a ratio of at least 40% of total weight into the mixing chamber of an extrusion machine and extruded through a classical sheet die into a thin cathode sheet or film onto a substrate in sheet form.

[0001] This application is a continuation of application Ser. No.10/382,539 filed Mar. 7, 2003.

FIELD OF THE INVENTION

[0002] The present invention relates generally to alkali metal polymerbatteries and, more specifically, to positive electrode sheets foralkali metal polymer batteries made by a continuous extrusion processfor forming solid polymer electrolyte-cathode sheets.

BACKGROUND OF THE INVENTION

[0003] Rechargeable batteries manufactured from laminates of solidpolymer electrolytes and sheet-like electrodes display many advantagesover conventional liquid electrolytes batteries. These advantagesinclude: lower overall battery weight, high power density, high specificenergy, and longer service life. In addition, they are moreenvironmentally friendly since the danger of spilling toxic liquid intothe environment is eliminated.

[0004] Solid polymer battery components generally include: positiveelectrodes (also referred to as cathodes), negative electrodes (alsoreferred to as anodes), and an insulating material capable of permittingionic conductivity, such as a solid polymer electrolyte, sandwichedtherebetween. The anodes electrodes are usually made of light-weightmetals foils, such as alkali metals and alloys thereof typically lithiummetal, lithium oxide, lithium-aluminum alloys and the like. Thecomposite cathodes or positive electrodes are usually formed of amixture of active material such as a transitional metal oxide, anelectrically conductive filler, usually carbon particles, an ionicallyconductive polymer electrolyte material and a current collector usuallya thin sheet of aluminum.

[0005] Composite cathode films are usually obtained by coating onto acurrent collector a mixture of a solvent and cathode materials with adoctor blade, for instance, and evaporating the solvent. This process isinefficient for the mass production of cathode films and results incathode films having a relatively high porosity, and therefore decreaseddensity.

[0006] Since solid polymer electrolytes are usually less conductive thanliquid polymer electrolytes, solid or dry electrochemical cells must beprepared from very thin films (total thickness of approximately 35 to250 microns) to compensate for the lower conductivity, with a high filmcontact surfaces and provide electrochemical cells with high powerdensity. Solid cathode films must therefore be produced into very thinfilms of generally ranging from about 35 to 125 microns.

[0007] One of the most efficient manufacturing processes for obtainingthin sheets is the process of continuous extrusion. U.S. Pat. No.5,725,822 to Keller et al. discloses a method for extruding electrodematerial by liquid injection. The solid particulate of active electrodematerials are partially mixed with a minor portion of the components ofthe polymer electrolyte and fed into a first feed throat of the extruderwhile the remaining polymer electrolyte composite, preferably rich inliquid components including at least one solvent, is fed downstreamthrough a second feed throat. The process has been found to provide acomposite having a high ratio of solid active materialelectrode/electrolyte and by separately mixing the components, theelectrode composition may be adjusted to provide optimal proportions ofall materials for a given application. However, this process is limitedto polymer electrolyte binders capable of withstanding the extrusionprocessing conditions, in particular the temperature, pressure and shearconditions such as polyacrylonitrile (PAN), polyvinylidene difluoride(PVDF), polyvinylpyrrolidone (PVP) and the like mixed with a solvent.The use of solvent into the extruded mixture results in a thickercomposite cathode sheet that displays a high porosity and a roughsurface finish. The latter characteristics are generally detrimental tothe efficiency of the electrochemical cell produced.

[0008] U.S. Pat. No. 5,316,556 to Morris also discloses an apparatus andmethod for extruding a cathode in which the cathode material is mixed toan homogenous state, and then transported under constant or increasingshear stress to a point of extrusion such that it is extruded atconstant rate. The cathode material disclosed is referred to as a shearthinning material as it exhibits non-Newtonian fluid characteristics;that is its viscosity decreases as the material is subjected toincreasing shear stress. The solution proposed to transport the melted‘shear thinning’ cathode material smoothly to the extruder exit nozzleis simply to maintain a minimum pressure and therefore a minimum amountof shear stress on the ‘shear thinning’ cathode material to ensure thatthe viscosity or flow resistance of the cathode material remains below acertain value to prevent blockage of the cathode material in theextruder. Experience has shown however that such a simple technique isinadequate for a wide variety of cathode material especially when thesolid content of the cathode material is above 30% by weight.

[0009] Cathode materials having a high solid content of active cathodicmaterial and conductive filler (above 30%) like polymers of thepolyether family such as polyethylene oxide having a high percentage ofsolid particles of vanadium oxide and carbon cannot withstand normalextrusion conditions and, more particularly, high temperatures and highshear conditions. Polyethers have a low melting point (around 50° C.)and are chemically unstable under extrusion conditions thereby makingthem extremely difficult to process through an extruder to form a thinpositive electrode composite sheet. Neither Keller et al. nor Morrisprovide a viable process for extruding cathode thin films made of apolyether binder having a high percentage of solids.

[0010] Thus there is a need for a thin solid polymer electrolyte-cathodesheet having a high solid content which can be extruded and a method forextruding a cathode sheet having a high solid content.

SUMMARY OF THE INVENTION

[0011] Under a first broad aspect, the invention seeks to provide apositive electrode film for an alkali metal polymer battery, thepositive electrode thin film comprises an ionically conductive polyetherelectrolyte material, an active cathodic intercalation material, alithium salt, and Carbon and Graphite particles as electronicallyconductive materials in a ratio of Carbon/Graphite ranging from about0.1:1 to 4:1. The positive electrode film comprises at least 40%/wt ofactive cathodic intercalation material, lithium salt; and Carbon andGraphite particles.

[0012] Preferably, the positive electrode thin film comprises more than50%/wt of active cathodic intercalation material; lithium salt; andCarbon and Graphite particles; the thickness of the positive electrodethin film is between about 35 microns and about 125 microns and theratio of Carbon/Graphite ranges from about 0.5:1 to 2:1 Advantageously,the positive electrode thin film further comprises an additiveconsisting of an ultra fine powder of metal oxide such as fumed silica,aluminum, or titanium oxide with a particle size between about 7 and 40nm.

[0013] Under a second broad aspect, the invention also seeks to providea process for extruding a positive electrode sheet having at least40%/wt of solid content for an alkali metal polymer battery through asingle or twin screw extruder. The process comprises:

[0014] (a) introducing a polyethylene oxide in a first feed throat ofthe extruder;

[0015] (b) introducing downstream from the first feed throat, a mixtureof active cathodic intercalation material, lithium salt and electronicconductive material; said mixture being introduced in a quantitysufficient to be at least 40%/wt of the positive electrode sheet to beproduced;

[0016] (c) mixing the polyethylene oxide with the mixture introduced in(b) into a single or twin screw section of said extruder;

[0017] (d) extruding a positive electrode material obtained in c)through a die in the form of a sheet; and

[0018] (e) depositing the positive electrode material onto a substrate.

[0019] Advantageously, the thickness of the positive electrode sheet isfurther reduced by calandering, laminating or rolling the extrudedpositive electrode sheet and/or by stretching the positive electrodesheet onto the substrate by selecting a speed of the substrate at ornear the die opening of the extruder such that the speed of thesubstrate exceeds the rate of discharge of the positive electrodematerial through thereby reducing the thickness of the positiveelectrode sheet deposited thereon. Preferably, the final thickness ofthe positive electrode sheet is between about 25 microns and about 125microns and more preferably between about 35 microns and about 70microns.

[0020] Under a third broad aspect, the invention further seeks toprovide an electrochemical cell comprising a lithium or lithium alloybased negative electrode, a solid polymer electrolyte separator and apositive electrode film. The positive electrode film comprises anionically conductive polyether electrolyte material, an active cathodicintercalation material, a lithium salt, and Carbon and Graphiteparticles as electronically conductive materials in a ratio ofCarbon/Graphite ranging from about 0.1:1 to 4:1. The positive electrodefilm comprises at least 40%/wt of active cathodic intercalationmaterial, lithium salt; and Carbon and Graphite particles.

[0021] Under a fourth broad aspect, the invention seeks to provide aprocess for extruding a positive electrode sheet having at least 40%/wtof solid content through a single or twin screw extruder. The processcomprises: mixing a polymer binder, an active cathode material, and anelectronic conductive material into a single or twin screw section ofthe extruder; extruding a positive electrode material through a dieopening in the form of a sheet; feeding the positive electrode materialbetween a pair of rollers; and depositing the positive electrodematerial onto a substrate traveling near the rollers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] A detailed description of preferred embodiments of the presentinvention is provided herein below with reference to the followingdrawings, in which:

[0023]FIG. 1A is a schematic cross-sectional side view of a typical twinscrew extrusion machine illustrating the inner parts and channels of theextrusion machine;

[0024]FIG. 1B is a schematic top plan cross-sectional view of a typicaltwin screw extrusion machine illustrating the inner parts and channelsof the extrusion machine;

[0025]FIG. 2A is a schematic front view of the extrusion die showing thepositive electrode film being extruded onto a substrate;

[0026]FIG. 2B is a schematic front view of the extrusion die showing thepositive electrode film being extruded directly onto rollers;

[0027]FIG. 2C is a schematic front view of the extrusion die showing thepositive electrode film being extruded directly onto rollers and routedaround one of the rollers.

[0028]FIG. 3 is a schematic front view of two extrusion stations; and

[0029]FIGS. 4A to 4D are schematic top plan views of the innerconfiguration of typical sheet dies.

[0030] In the drawings, preferred embodiments of the invention areillustrated by way of examples. It is to be expressly understood thatthe description and the drawings are only for the purpose ofillustration and as an aid to understanding. They are not intended to bea definition of the limits of the invention.

DETAILED DESCRIPTION

[0031] With reference to FIGS. 1A and 1B, there is shown a typical twinscrew extruding machine 10 having a pair of screws 12 and 14 powered bystandard electric motors 16. Screws 12 and 14 feature threads 20 and acentral shaft 18 having an increasing diameter such that the materialbeing mixed into the mixing chamber 15 is intimately mixed and undervarying pressure as it is transported in the direction X. Extrudingmachine 10 further comprises a first feed throat 24 at a first end ofthe mixing chamber 15 and a second feed throat 26 located approximatelynear the middle of mixing chamber 15. The forward end 17 of mixingchamber 15 is of conical shape to direct the melted material beingtransported into a gear pump 22 provided to control the flow rate of themelted material exiting mixing chamber 15. On the exit side of gear pump22 is an elbow-shaped conduit 28 leading to a die 30 through which themelted material is discharged at constant rate onto a substrate sheet orfilm 32 traveling at constant speed. Commercially available extrudingmachines featuring single or twin screw design may be used for themixing and melting process however it has been found that twin screwdesigned extruding machine provides a superior mixing of the componentsof the cathode material.

[0032] As shown more specifically in FIG. 1a, vents 23 and 25 arefeatured along the upper wall of mixing chamber 15 to eliminate volatilematter still remaining in the polymer during the heating and mixingprocess. Two vents are depicted in this particular embodiment, howeverany number of vents may be provided depending on the amount of volatilematter still remaining in the polymer. Vents 23 and 25 are locatedapproximately between the central axis of twin screws 12 and 14 suchthat melted material will not be push out through vents 23 and 25 by therespective action of screws 12 and 14. The configuration of the screwsprovides for two decompression zones substantially aligned with vents 23and 25 and two mixing zones located before each vent 23 and 25. In thedecompression zones, the thread pitch of the screws or screw is greaterthan in the mixing zones thereby reducing the pressure of the meltedmaterial and preventing spillage of the melted material through thevents. The configurations of screws 12 and 14 provides for anhomogeneous cathode material without degrading its polymer component.

[0033] The cathode or positive electrode material according to theinvention preferably includes a mixture of ionically conductive polymerelectrolyte material such as polyethylene oxide, active cathodicmaterial such as vanadium oxide, an electrically conductive filler suchas carbon and graphite particles, and lithium salt. In a preferredembodiment, the positive electrode material includes between 25%/wt and30%/wt of polyethylene oxide; between 57%/wt and 67%/wt. of vanadiumoxide; between 1.5%/wt and 5%/wt of carbon and graphite particles; andbetween 4%/wt and 10%/wt of lithium salt. A small portion of fumedsilica and some antioxidant in minute proportion may also be added tothe mixture in some instances.

[0034] Plasticizers or lubricants in small quantity (less than 10%/wt)may also be included in the polymer to enhance mixing of the polymerwith the solid content outlined above and/or to reduce the viscosity ofthe mixture to facilitate the extrusion of the composite cathodematerial. Plasticizers or lubricants such as polyvinylidene fluoride(PVDF), co-polymer polyvinylidene fluoride/hexafluoroisopropanol(PVDF-HFP) polyvinyl fluoride (PVF), polyethylene glycol dimethyl ether,tetraglyme, triglyme, ethylene carbonate, propylene carbonate, EO/POdiglycol and EO/PO monoglycol or distearates may be used to that effect.Preferably, fluoride polymers such as PVDF, PVDF-HFP, and PVF orpolyethylene glycol dimethyl ether are added to the polymer in smallquantity; these polymers do not significantly reduce the ionicconductivity or the solid character of the cathode material beingextruded. Water may also be used as a plasticizer to reduce theviscosity of the compound and ease of mixing of the solid content withthe polyethylene oxide in proportion ranging from 0.005% up to 5% andpreferably between 0.1% and 0.8%. The water is dissipated in vaporduring the mixing and melting process in the mixing chamber 15.

[0035] The vanadium oxide particle size is selected such as to enable anadequate mixture of the vanadium oxide with the polyethylene oxide inmixing chamber 15. Preferred particle sizes of vanadium oxide range fromabout 0.3 micron to about 20 microns.

[0036] Polyethylene oxide is introduced into mixing chamber 15 throughthe first feed throat 24 where it begins to melt. Vanadium oxide LiV3O8,carbon and graphite particles in a ratio of about 1:1, and optionally anultra fine powder of fumed silica are pre-mixed into reservoir 34 andthen introduced into mixing chamber 15 through the second feed throat26. Salt based on lithium are introduced into mixing chamber 15 throughthe second feed throat 26, however the lithium salt may be introducedthrough a third feed throat (not shown) located between first feedthroat 24 and second feed throat 26. As well, plasticizers or lubricantsas described above may be mixed with the polyethylene oxide prior tointroduction into the mixing chamber 15 or may be introduced into mixingchamber 15 through second feed throat 26 with a view of modifying theTheological properties of the slurry such as reducing the viscosity ofthe cathode slurry and/or promoting the mixing of the solid content withthe polyethylene oxide. In mixing chamber 15, the pre-mixed componentsoutlined above are further mixed with the polyethylene oxide through theactions of the twin screws and blended into an homogeneous slurry whichis transported under pressure in direction X to the forward end 17 ofmixing chamber 15. The slurry is pushed into gear pump 22 whichregulates or controls the flow rate of the slurry through conduit 28 andultimately though die 30. As the cathode slurry enters die 30, its flowpath is reshaped such that the cathode material slurry exits die 30shaped as a thin film of between 40 and 200 microns and is depositedonto a thin sheet substrate 32 of polypropylene or polyethylene or athin metal foil such as an aluminum or copper foil.

[0037] As shown in FIG. 2a, in an embodiment of the continuousmanufacturing process of a thin film positive electrode for an alkalimetal polymer electrochemical cell, the cathode or positive electrodefilm 36 exiting die 30 is deposited between a pair of travelingsubstrate sheets 38 and 40 supported and driven at constant speed by apair of flat cylinder rollers 42. In a preferred embodiment, cathodefilm 36 is deposited between a current collector sheet 40 and apolypropylene sheet 38. Cathode film 36 is deposited directly onto thecurrent collector of the electrochemical cell being produced.Preferably, die 30 is oriented vertically and is positioned as close aspossible to the pair of flat cylinder rollers 42. The three-layer film44 is then carried away and rolled up for storage or transported tofurther processing stations to complete the assembly of the alkali metalpolymer electrochemical cell. Various cylinders 46 are provided alongthe path of the substrate films 38 and 40 and the three-layer film 44 toprovide the required tension such that the films remain flat. To preventadhesion of the films or sheets to the flat cylinder rollers 42, thelatter are maintained at temperatures below the ambient temperature andpreferably at a temperature generally ranging from about −5° C. to about−30° C. Flat cylinder rollers 42 may also be provided with ananti-adhesive liner to prevent such adhesion.

[0038] Flat cylinder rollers 42 are mounted on pivotal supportstructures 48 and 50, each having an hydraulic cylinder 52 adapted toadjust the position of the cylinder rollers 42 and to also to adjust thepressure applied onto the three-layer film 44 as it passes in betweenthe cylinder rollers 42. It should be expressly understood that othermeans for adjusting the position of the cylinder rollers 42 and thepressure applied on the three-layer film 44 by the cylinder rollers 42are contemplated and within the reach of a person skilled in the art,and as such are within the scope of the present invention. Although thecathode film 36 already features smooth surfaces, the pressure appliedby cylinder rollers 42 equalizes the surface finish of both surfaces toprovide a smooth and even surface. The surface finish or roughness ratioof the extruded cathode material is important to the efficiency of ionicexchange between the electrolyte separator and the cathode of theelectrochemical cell to be assembled. The ionic exchange efficiencydiminishes with the coarseness of the cathode surface.

[0039] The pressure applied on the positive electrode film 36 may alsobe used to further reduce its thickness. The final thickness of thecathode film 36 should be between about 25 and 125 microns, andpreferably between about 35 and 70 microns. Cathode film 36 may beextruded at a thickness of up to 250 microns, and then reduced bylamination, calendaring, or rolling as is well known in the art to thedesired thickness. However in a preferred embodiment of the invention,the cathode film 36 is extruded at a thickness of about between 35 and70 microns directly onto substrate 32 of polypropylene or polyethyleneor the current collector in the form of aluminum or copper foil.

[0040] As a variant of the manufacturing process, the extruded cathodefilm 36 may also be stretched onto the substrate 32 in order to reduceits final thickness. The stretching of the extruded cathode material isachieved by selecting the speed at which the substrate 32 travels at thecontact point between the extruded cathode material and the substrate 32near exit of die 30 such that the speed of substrate 32 exceeds the rateof discharge of the cathode material at the die opening. The speeddifferential between the substrate 32 and the cathode material exitingdie 30 will stretch the cathode film 36 thereby reducing its thickness.

[0041]FIG. 2B illustrates another embodiment of the continuousmanufacturing process of a positive electrode film or cathode film foralkali metal polymer electrochemical cells. In this embodiment, thecathode film 36 exiting die 30 is deposited directly between flatcylinder rollers 42 that are maintained at cool temperatures. Thisparticular method eliminates any problems that may occur if thesubstrate films 38 or 40 of the previous embodiment rip or break underthe pulling tension exerted by flat cylinder rollers 42. As shown inFIG. 2B, cathode film 36 exits die 30 in the form of a relatively thinsheet; the sheet 36 is taken up directly by the pair of flat cylinderrollers 42 which equalizes the thickness and surface finish of film 36to provide a smooth and even surface. Flat cylinder rollers 42 may alsoreduce the thickness of the film 36 to its final thickness of aboutbetween 35 and 70 microns, if the film 36 exits die 30 with a thicknessexceeding the target thickness of 35 to 70 microns. As previouslymentioned, flat cylinder rollers 42 are maintained at temperatures belowthe ambient temperature and preferably at a temperature ranging fromabout −5° C. to about −30° C. to prevent adhesion of the film 36 to theflat cylinder rollers 42. Flat cylinder rollers 42 may also be providedwith an anti-adhesive liner. The film 36 is then laminated onto asubstrate 80, preferably a current collector substrate, traveling belowflat cylinder rollers 42. The laminate 84 may then pass between a secondpair of flat cylinder rollers 82 to promote adhesion of the cathode film36 onto the substrate 80. As shown in FIG. 2C, the duration of contactbetween the extruded cathode film 36 and one of the cooled flat cylinderrollers 42 may be controlled by routing the cathode film 36 around anidle cylinder 46 in order to increase heat transfer efficiency. Asillustrated in FIG. 2C, cathode film 36 remains in contact with one ofthe cooled cylinder rollers 42 through nearly 180 of rotation of thecooled cylinder rollers 42 thereby increasing the total heat transferbetween the cathode film 36 and one of the cooled flat cylinder rollers42.

[0042] As previously described, the cathode film 36 obtained via theembodiment illustrated in FIG. 2B may also be stretched to reduce itsfinal thickness. The stretching of the extruded cathode material isachieved by selecting a rotating speed of the flat cylinder rollers 42that exceeds the rate of discharge of the cathode material at the dieopening. The speed differential between the rotating speed of the flatcylinder rollers 42 and the cathode material exiting die 30 will stretchthe cathode film 36 thereby further reducing its thickness.

[0043] Another embodiment in which the cathode film 36 is depositedbetween the current collector and one of the flat cylinder rollers 42 isalso contemplated, wherein the cathode film 36 is pressed directlybetween the surface of the roller 42 on one side and the currentcollector on the other side.

[0044] The positive electrode material or cathode material as describedabove is a very difficult material to extrude because of its high solidcontent, yet the content of active material in solid form in the cathodeis relatively important. The more active material in the cathode, thebetter the performance of the finished product. The polyethylene oxideelectrolyte is a binder and does not contribute to the energy content ofthe electrochemical cell being produced therefrom. However, a high solidcontent into the polyethylene oxide binder increases the extrusiontemperature, the shear stress to which the mixture of cathode materialis subjected to, and therefore increases the degradation of thepolyethylene oxide binder making it difficult to extrude a positiveelectrode that will perform to specification. Furthermore, the lithiumsalt (TFSI) included in the positive electrode material increases ionicconductivity of the cathode but reduces the viscosity of the positiveelectrode material thereby increasing the difficulty of transporting thepositive electrode/cathode slurry through mixing chamber 15, conduit 28and die 30.

[0045] Typical cathode material for an alkali metal polymerelectrochemical cell comprises carbon black as the only electricallyconductive filler. However, carbon black has extremely small particles(sub microns). When mixed into the cathode material, the high surfacearea of these small particles are coated with a substantial portion ofthe polyethylene oxide binder which has the negative effect ofdecreasing the solid content of active material which can be absorbed bythe polyethylene oxide binder. Carbon black particles also createagglomeration of the mixture, thereby increasing the likelihood ofblockage in an extruder and generally increasing the viscosity of themixture. Graphite however displays an acceptable electronic conductivityand comprises larger particles having therefore less surface area to becoated by the polyethylene oxide binder with the effect of decreasingthe viscosity of the mixture. Utilizing a blend of carbon black/graphitein the cathode material as opposed to only carbon permits a higher solidactive material content in the cathode mixture and reduces the overallviscosity and potential blockage of the cathode mixture in the extruderwithout significantly reducing the electronic conductivity of thecathode.

[0046] Into the mix of cathode material in reservoir 34, an additiveconsisting of an ultra fine powder of metal oxide such as silica,aluminum, or titanium oxide with a particle size between about 7 and 40nm as disclosed in U.S. Pat. No. 5,486,435 and U.S. Pat. No. 5,622,792both of which are hereby incorporated by reference, may also beintroduced. The role of the additive is to prevent or diminish theformation of adhesive solid blocks in the powder mixture in reservoir 34and to allow its introduction into the second feed throat of theextruder. Preferred compositions of ultra fine powders of metal oxideinclude pyrogenated silica having a BET surface between 50 and 400 m2/gcontaining more than 99.8% silica in a concentration of less than 10% byweight with respect to the mixture of cathode material.

[0047] As previously mentioned, plasticizers or lubricants in smallquantity (less than 5%/wt) may also be included in the polymer tooptimize the mixing ability of the components of the cathode mixture andthe viscosity of the mixture to facilitate the extrusion of thecomposite cathode material.

[0048] The extrusion process and the mixture of cathode materialdescribed above enables the extrusion of a positive electrode filmhaving a total solid content by weight of between about 40 and 80percent using a commercially available extrusion machine. Extruding thecathode material according to the invention provides a cathode having aporosity of less than 10%.

[0049]FIG. 3 illustrates another variant of the manufacturing process,in which a single current collector is coated on both sides with apositive electrode or cathode film. The current collector thin sheet 70,preferably comprising aluminum, is brought into a first extrusionstation “A” comprising an extrusion machine 72 similar to the onedepicted in FIG. 2A or 2B where a positive electrode film is depositedby die 30 onto a first side of current collector 70. The two layer film74 passes through a pair of rollers 42 which are controlled by eitherhydraulic or electric actuators 76, and then exits extrusion station“A”. The two layer film 74 enters into a station “C” where it is turnedupside down such that it exits station “C” with its layer of positiveelectrode film facing down. The face down two layer film 74′ istransported into a second extrusion station “B” comprising an extrusionmachine 72 where another positive electrode film is deposited by a die30 onto the second side of the current collector such that both sides ofthe current collector are coated with a positive electrode film 36. Theresulting three layer film 74″ of current collector/twin positiveelectrodes then exits the second extrusion station “B” and is eitherrolled up for storage or transported to further processing stations tocomplete the assembly of the alkali metal polymer electrochemical cell.

[0050] The cathode material may be extruded through any classical sheetdies, such as those illustrated in FIGS. 4A to 4D, into a cathode sheetor film. The shape of typical sheet dies may come in a variety ofdesigns such as with a fish tail inner configuration or a coat hangerinner configuration. A sheet die spreads the flow path of the cathodematerial over a wide surface and enable to extrude into thin sheets. Forthe extrusion of very thin sheets as described herein, channels may becarved into the die to direct an increased flow of cathode materialtoward the sides of the die exit to ensure that the cathode sheet beingextruded has an even thickness throughout its width.

[0051] Although the present invention has been described in relation toparticular variations thereof, other variation and modifications arecontemplated and are within the scope of the present invention.Therefore the present invention is not to be limited by the abovedescription but is defined by the appended claims.

What is claimed is:
 1. A method for combining electrode componentscomprising: an active material, an ionically-conductive polymer, anelectrolyte salt, and no added solvent, the method comprising processingthe electrode components using a single screw extruder.
 2. The method ofclaim 1 wherein the combined electrode components include a total ofless than 0.8 percent by weight solvent.
 3. The method of claim 1wherein the combined electrode components include a total of less than0.1 percent by weight solvent.
 4. The method of claim 1 whereincomprises active material selected from the group consisting of oxidesof vanadium, its lithiated versions, and mixtures thereof.
 5. The methodof claim 1 wherein the electrode components comprise at least 40%/wt ofsaid active material.
 6. The method of claim 1 wherein the electrodecomponents comprise at least 50%/wt of said active material.
 7. Themethod of claim 1 wherein the electrode components comprise at least60%/wt of said active material.
 8. The method of claim 1 wherein theelectrode components comprise from about 57-67 weight percent activematerial.
 9. The method of claim 1 wherein the electrode componentsfurther comprise electrically-conductive material comprising carbonblack, graphite, or a combination thereof.
 10. The method of claim 9wherein the electrically-conductive material comprises a mixture ofcarbon and graphite in a ratio of carbon/graphite ranging from about0.5:1 to 2:1.
 11. The method of claim 1 wherein the ionically-conductivepolymer is selected from the group consisting of: polymers or copolymersof ethylene oxide, and cyclic ether oxides.
 12. The method of claim 11wherein the ionically-conductive polymer comprises a polyethylene oxide.13. The method of claim 1 wherein the electrolyte salt comprises alithium salt.
 14. The method of claim 13 wherein the lithium salt isTFSI bis(trifluoromethanesulfonyl)imide salt.
 15. A method for combiningelectrode components comprising: an active material, anionically-conductive polymer, an electrolyte salt, wherein the methodcomprises processing the electrode components using a single screwextruder and wherein the electrode components are processed in a moltenstate. 16 A method of producing a battery cathode, the methodcomprising: processing a mixture of ingredients comprising greater thanabout 50 weight percent active material, from about 1 to about 10 weightpercent electrically-conductive material comprising carbon black,graphite, or a combination thereof, from about 10 to about 40 weightpercent polymer comprising ionically-conductive polyethylene oxidepolymer, from about 4 to about 10 weight percent lithium salt, whereinthe mixture includes a total of less than about 0.8 percent by weightsolvent, the method comprising using a single or twin screw extruder andprocessing the mixture in a molten state.
 17. A method for combiningelectrode components comprising: an active material, anionically-conductive polymer, an electrolyte salt, and no added solvent,the method comprising processing the electrode components using a twinscrew extruder.
 18. The method of claim 17 wherein the combinedelectrode components include a total of less than 0.8 percent by weightsolvent.
 19. The method of claim 17 wherein the combined electrodecomponents include a total of less than 0.1 percent by weight solvent.20. The method of claim 17 wherein comprises active material selectedfrom the group consisting of oxides of vanadium, its lithiated versions,and mixtures thereof.
 21. The method of claim 17 wherein the electrodecomponents comprise at least 40%/wt of said active material.
 22. Themethod of claim 17 wherein the electrode components comprise at least50%/wt of said active material.
 23. The method of claim 17 wherein theelectrode components comprise at least 60%/wt of said active material.24. The method of claim 17 wherein the electrode components comprisefrom about 57-67 weight percent active material.
 25. The method of claim17 wherein the electrode components further compriseelectrically-conductive material comprising carbon black, graphite, or acombination thereof.
 26. The method of claim 25 wherein theelectrically-conductive material comprises a mixture of carbon andgraphite in a ratio of carbon/graphite ranging from about 0.5:1 to 2:1.27. The method of claim 17 wherein the ionically-conductive polymer isselected from the group consisting of: polymers or copolymers ofethylene oxide, and cyclic ether oxides.
 28. The method of claim 27wherein the ionically-conductive polymer comprises a polyethylene oxide.29. The method of claim 17 wherein the electrolyte salt comprises alithium salt.
 30. The method of claim 29 wherein the lithium salt isTFSI bis(trifluoromethanesulfonyl)imide salt.
 31. A method for combiningelectrode components comprising: an active material, anionically-conductive polymer, an electrolyte salt, and no added solvent,the method comprising processing the electrode components using areciprocating single screw extruder.
 32. The method of claim 31 whereineach electrode component contains essentially no solvent.
 33. The methodof claim 31 wherein each electrode component is a dry material thatcontains no solvent.
 34. The method of claim 31 wherein the combinedelectrode components include essentially no solvent.
 35. The method ofclaim 31 wherein the combined electrode components include a total ofless than 0.5 percent by weight solvent.
 36. The method of claim 31wherein the active material comprises a metal oxide.
 37. The method ofclaim 31 wherein the active material comprises a metal oxide selectedfrom the group consisting of oxides of vanadium, manganese, cobalt,nickel, chromium, aluminum, tungsten, molybdenum, titanium, theirlithiated versions, and mixtures thereof.
 38. The method of claim 31where the active material comprises a vanadium oxide.
 39. The method ofclaim 31 wherein the electrode components comprise from about 50-86weight percent active material.
 40. The method of claim 31 wherein theelectrode components comprise from about 60-68 weight percent activematerial.
 41. The method of claim 31 wherein the components furthercomprise electrically-conductive material comprising carbon black,graphite, or a combination thereof
 42. The method of claim 31 whereinthe ionically-conductive polymer comprises a derivative of monomerscomprising an oxygen-containing monomer or a nitrogen-containingmonomer.
 43. The method of claim 31 wherein the ionically-conductivepolymer comprises a polyalkylene oxide polymer or copolymer.
 44. Themethod of claim 31 wherein the electrolyte salt comprises a fluorinatedlithium salt.
 45. The method of claim 31 wherein the electrolyte salt ischosen from the group consisting of lithium hexafluoroarsenate, lithiumperchlorate, lithium hexafluorophosphate, lithium trifluoroborate,lithium trifluoromethanesulfonate, lithiumbis(trifluoromethanesulfonyl)imide, lithiumbis(perfluoroethanesulfonyl)imide, lithiumtris(trifluoromethanesulfonyl)methide, and mixtures thereof.
 46. Themethod of claim 31 wherein the electrode components comprise: greaterthan about 50 weight percent active material, from about 1 to about 10weight percent electrically-conductive material comprising carbon black,graphite, or a combination thereof, from about 10 to about 40 weightpercent ionically-conductive polymer, from about 3 to about 15 weightpercent lithium salt, and less than about 0.5 weight percent solvent.47. The method of claim 46 wherein the active material comprises a metaloxide selected from the group consisting of oxides of vanadium,manganese, cobalt, nickel, chromium, aluminum, tungsten, molybdenum,titanium, their lithiated versions and mixtures thereof.
 48. The methodof claim 46 where the ionically-conductive polymer comprises aderivative of monomers comprising an oxygen-containing monomer or anitrogen-containing monomer.
 49. The method of claim 46 wherein theionically-conductive polymer comprises a polyalkylenoxide polymer orcopolymer.
 50. The method of claim 46 wherein the lithium salt is chosenfrom the group consisting of lithium hexafluoroarsenate, lithiumperchlorate, lithium hexafluorophosphate, lithium trifluoroborate,lithium trifluoromethanesulfonate, lithiumbis(trifluoromethanesulfonyl)imide, lithiumbis(perfluoroethanesulfonyl)imide, lithiumtris(trifluoromethanesulfonyl)methide, and mixtures thereof.
 51. Themethod of claim 31 wherein the extruder comprises multiple feed inletsand a downstream extruding end, and wherein the ionic salt feeds intothe extruder at a first feed position, the ionically-conductive polymer,the active material, and the electrically-conductive material each feedinto the extruder at one or more feed positions downstream from theionic salt feed position.
 52. The method of claim 51 wherein theionically-conductive polymer feeds into the extruder as a solidcontaining no solvent.
 53. The method of claim 51 wherein theionically-conductive polymer feeds into the extruder as a melt.
 54. Themethod of claim 51 wherein the ionically-conductive polymer feeds intothe extruder at a second position downstream from the first feedposition, and a mixture comprising active material andelectrically-conductive material is fed at a third feed positiondownstream from the second feed position.
 55. The method of claim 51wherein ionically-conductive polymer, active material, andelectrically-conductive material are combined and fed into the extruderas a single mixture at a second feed position.
 56. The method of claim51 wherein a mixture comprising active material, electrically-conductivematerial, and ionically-conductive polymer is fed at a second feedposition, and a mixture comprising active material andelectrically-conductive material is fed at a third feed positiondownstream from the second feed position.
 57. A method for combiningelectrode components comprising: an active material, anionically-conductive polymer, an electrolyte salt, wherein the methodcomprises processing the electrode components using a reciprocatingsingle screw extruder and wherein an ionically-conductive polymer saltcomplex material is processed in a molten state.
 58. A method ofproducing a battery cathode, the method comprising processing a mixtureof ingredients comprising: greater than about 50 weight percent activematerial, from about 1 to about 10 weight percentelectrically-conductive material comprising carbon black, graphite, or acombination thereof, from about 10 to about 40 weight percent polymercomprising ionically-conductive polyalkylenoxide polymer, from about 3to about 15 weight percent fluorinated lithium salt, wherein the mixtureincludes a total of less than about 0.5 percent by weight solvent, themethod comprising using a reciprocating extruder and processing anionically-conductive polymer salt complex in a molten state.
 59. Themethod of claim 58 further comprising depositing an extrudate of theelectrode components onto a substrate.
 60. The method of claim 59wherein the substrate is chosen from the group consisting of a liner, acurrent collector, a separator, or an electrolyte.
 61. The method ofclaim 58 wherein the ingredients include at least about 50 weightpercent active ingredient.
 62. The method of claim 58 wherein theingredients include at least about 60 weight percent lithiated vanadiumoxide.
 63. A method for combining electrode components comprising:ionically-conductive polymer, electrolyte salt, the method comprisingprocessing electrolyte components using a reciprocating single screwextruder, wherein ionically-conductive polymer is fed to the extruderdownstream from electrolyte salt.
 64. The method of claim 63 wherein theionically-conductive polymer feeds into the extruder as a melt.
 65. Themethod of claim 63 wherein the electrode components contain no addedsolvent.
 66. The method of claim 63 wherein the components furthercomprise active material.